Get all user properties from Microsoft graph

We have an application which has used a local AD to fetch user info. Some customers want to move to the cloud and are using Azure AD. We extended the app to sign users in via owin and now we're fetching users via Microsoft Graph.

However from Microsoft Graph we do not get full user profiles. We want to fetch all properties on users, not just the basic ones.

var client = new RestClient(string.Format("https://graph.microsoft.com/v1.0/users/{0}", userEmail));
request = new RestRequest();
request.Method = Method.GET;
request.AddHeader("Authorization", _token.Token);
var reponse = client.Execute(request);

This only gives me some information though, for example I don't get 'Department' from this. Is it possible to configure in azure what should be returned here, if so then where? Or do I need something other than /users/?

Different customers might have different special properties that need to be fetched. So the best solution would be to have an endpoint to call and get everything, including special properties not standard in azure ad. After that I can parse it on my side. Is this possible?

The app has permission to read both basic and full profiles. Do I need something more?

That's the normal behaviour of Graph API, see documentation here and this extract:

This operation returns by default only a subset of the more commonly used properties for each user. These default properties are noted in the Properties section. To get properties that are not returned by default, do a GET operation for the user and specify the properties in a $select OData query option. Because the user resource supports extensions, you can also use the GET operation to get custom properties and extension data in a user instance.

You have to specify all fields in the select, as $select=* will only output the key fields in Graph API implementation.

So you will not be able to get what you ask (variable custom fields).

More info on the fields of User can be found here