diff --git a/client.go b/client.go
index d783a58..0c36812 100644
--- a/client.go
+++ b/client.go
@@ -7,6 +7,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 )
 
 type HttpClient interface {
@@ -34,14 +35,17 @@ func NewMockClient(handler http.HandlerFunc) *Client {
 	}
 }
 
-func (c Client) newRequest(ctx context.Context, method string, url string, body interface{}) (*http.Request, error) {
+func (c Client) newRequest(ctx context.Context, method string, uri string, body interface{}) (*http.Request, error) {
 	bodyJson, err := json.Marshal(body)
 	if err != nil {
 		return nil, err
 	}
 
-	url = c.baseUrl + url
-	req, err := http.NewRequestWithContext(ctx, method, url, bytes.NewBuffer(bodyJson))
+	uri, err = url.JoinPath(c.baseUrl, uri)
+	if err != nil {
+		return nil, err
+	}
+	req, err := http.NewRequestWithContext(ctx, method, uri, bytes.NewBuffer(bodyJson))
 	if err != nil {
 		return nil, err
 	}
diff --git a/ozon/ozon.go b/ozon/ozon.go
index b6a783a..5ee6c8a 100644
--- a/ozon/ozon.go
+++ b/ozon/ozon.go
@@ -10,6 +10,15 @@ const (
 	DefaultAPIBaseUrl = "https://api-seller.ozon.ru"
 )
 
+type ClientOptions struct {
+	client core.HttpClient
+
+	baseUri string
+
+	apiKey   string
+	clientId string
+}
+
 type Client struct {
 	client *core.Client
 
@@ -110,10 +119,46 @@ func (c Client) Barcodes() *Barcodes {
 	return c.barcodes
 }
 
-func NewClient(httpClient core.HttpClient, clientId, apiKey string) *Client {
-	coreClient := core.NewClient(httpClient, DefaultAPIBaseUrl, map[string]string{
-		"Client-Id": clientId,
-		"Api-Key":   apiKey,
+type ClientOption func(c *ClientOptions)
+
+func WithHttpClient(httpClient core.HttpClient) ClientOption {
+	return func(c *ClientOptions) {
+		c.client = httpClient
+	}
+}
+
+func WithURI(uri string) ClientOption {
+	return func(c *ClientOptions) {
+		c.baseUri = uri
+	}
+}
+
+func WithClientId(clientId string) ClientOption {
+	return func(c *ClientOptions) {
+		c.clientId = clientId
+	}
+}
+
+func WithAPIKey(apiKey string) ClientOption {
+	return func(c *ClientOptions) {
+		c.apiKey = apiKey
+	}
+}
+
+func NewClient(opts ...ClientOption) *Client {
+	// default values
+	options := &ClientOptions{
+		client:  http.DefaultClient,
+		baseUri: DefaultAPIBaseUrl,
+	}
+
+	for _, opt := range opts {
+		opt(options)
+	}
+
+	coreClient := core.NewClient(options.client, options.baseUri, map[string]string{
+		"Client-Id": options.clientId,
+		"Api-Key":   options.apiKey,
 	})
 
 	return &Client{
diff --git a/ozon/ozon_test.go b/ozon/ozon_test.go
new file mode 100644
index 0000000..794ccf0
--- /dev/null
+++ b/ozon/ozon_test.go
@@ -0,0 +1,27 @@
+package ozon
+
+import (
+	"net/http"
+	"testing"
+)
+
+const (
+	apiKey   = "some_key"
+	clientId = "some_client_id"
+)
+
+func TestNewClient(t *testing.T) {
+	client := NewClient(
+		WithAPIKey(apiKey),
+		WithClientId(clientId),
+		WithURI(DefaultAPIBaseUrl),
+		WithHttpClient(http.DefaultClient),
+	)
+
+	if client.client.Options["Api-Key"] != apiKey {
+		t.Errorf("expected api key: %s, but got: %s", apiKey, client.client.Options["Api-Key"])
+	}
+	if client.client.Options["Client-Id"] != clientId {
+		t.Errorf("expected client id: %s, but got: %s", clientId, client.client.Options["Client-Id"])
+	}
+}