Cisco intra bss question

I have a question.
I'm working on a wireless network that will give clients free access to internet.
This will be city wide.
We did a pilot with pfsense (witch worked great) but we are looking for a more solid solution, so we went for Cisco.
I have 2 Air-cap3501 and a Cisco wireless controller 2504.
The question i have is how do i isolate clients from each other.
With pfsense i could check a box to block intra bss traffic but i can't find any option like this in the controller nor in the documentation from Cisco.
Can someone help me with this?

Is there a selection for Client Isolation?

http://www.cwnp.com/bbpress/topic.php?id=911

I'll check that tomorrow.
Hope it has that option.
Thanks

Hhhmm i could not find it on the controller nor in the documentation.
I'm searching via the command line interface now.
Any other suggestions?