[keycloak-user] Restrict user's access to a client on keycloak-3.4.3.Final

Hi all, I'm using keycloak-3.4.3.Final. For our UXP applications we delegate the authentication to Keycloak but we need to do some additional checks before granting access to the user. Our use case is quite simple: Not All registered users in Keycloak have access to our applications. So we need to insure that the user has permition to access our applications before granting him access to UXP. This is done in the backend. I tried to map roles to user and client but this does not work. Is there a way to achieve that? Thanks in advance. Rachid.