diff --git a/packages/gen-ai-hub/src/client/openai/openai-client.ts b/packages/gen-ai-hub/src/client/openai/openai-client.ts
index 9c949ff6..561821f5 100644
--- a/packages/gen-ai-hub/src/client/openai/openai-client.ts
+++ b/packages/gen-ai-hub/src/client/openai/openai-client.ts
@@ -1,6 +1,6 @@
 import { type HttpRequestConfig } from '@sap-cloud-sdk/http-client';
 import { type CustomRequestConfig, executeRequest } from '@sap-ai-sdk/core';
-import { pickValueIgnoreCase } from '@sap-cloud-sdk/util';
+import { mergeIgnoreCase, pickValueIgnoreCase } from '@sap-cloud-sdk/util';
 import {
   type DeploymentConfiguration,
   type FoundationModel,
@@ -100,16 +100,21 @@ function translateToFoundationModel(
   };
 }
 
-// TODO: merge headers and query params too?!
 function mergeRequestConfig(
   requestConfig?: CustomRequestConfig
 ): HttpRequestConfig {
   return {
     method: 'POST',
-    headers: {
-      'content-type': 'application/json'
-    },
-    params: { 'api-version': apiVersion },
+    headers: mergeIgnoreCase(
+      {
+        'content-type': 'application/json'
+      },
+      requestConfig?.headers
+    ),
+    params: mergeIgnoreCase(
+      { 'api-version': apiVersion },
+      requestConfig?.params
+    ),
     ...requestConfig
   };
 }
diff --git a/packages/gen-ai-hub/src/utils/deployment-resolver.test.ts b/packages/gen-ai-hub/src/utils/deployment-resolver.test.ts
index 71a949db..99bbafa7 100644
--- a/packages/gen-ai-hub/src/utils/deployment-resolver.test.ts
+++ b/packages/gen-ai-hub/src/utils/deployment-resolver.test.ts
@@ -19,13 +19,13 @@ describe('deployment resolver', () => {
       mockResponse();
     });
 
-    // it('should return the first deployment, if multiple are given', async () => {
-    //   const { id, configurationId } = await resolveDeployment({
-    //     scenarioId: 'foundation-models',
-    //   });
-    //   expect(id).toBe('1');
-    //   expect(configurationId).toBe('c1');
-    // });
+    it('should return the first deployment, if multiple are given', async () => {
+      const { id, configurationId } = await resolveDeployment({
+        scenarioId: 'foundation-models'
+      });
+      expect(id).toBe('1');
+      expect(configurationId).toBe('c1');
+    });
 
     it('should return the first deployment with the correct model name', async () => {
       const { id } = await resolveDeployment({
diff --git a/packages/gen-ai-hub/src/utils/deployment-resolver.ts b/packages/gen-ai-hub/src/utils/deployment-resolver.ts
index 57bd2796..fc31eb64 100644
--- a/packages/gen-ai-hub/src/utils/deployment-resolver.ts
+++ b/packages/gen-ai-hub/src/utils/deployment-resolver.ts
@@ -83,7 +83,7 @@ interface DeploymentResolutionOptions {
   /**
    * The name and potentially version of the model to look for.
    */
-  model: FoundationModel;
+  model?: FoundationModel;
   /**
    * The executable ID of the deployment.
    */