How to make my UI items/canvas stretch to fill preset aspect ratio

I have created a game in which the camera aspect stretches the view to fit a 16:9 aspect ratio but my UI elements don't stretch![alt text][1] like the other objects so the image is cut of at the top.

The UI should look like this:

However it is cut of on other resolutions:

The Code for the camera aspect:

 void Start () {
     Camera.main.aspect = 9f / 16f;
 }
 
 // Update is called once per frame
 void Update () {
 
 }

and the settings for my canvas are: Scale with screen - expand reference resolution: x = 1136 y = 640

Please help soon!