Use a portal to Contracts on your clients layout to list all contracts records for that client.
Use a script that either uses Go To Related Records or performs a find to both change to the contracts layout and also pull up just the contract records related to that client.
Your go to related records step might look like this:
Go To Related Record [Show only related records; From table: Contracts; Using layout: "Contracts" (Contracts)]
I think that should do the trick... Thanks :-)