Yes. There is a plugin called "User Access Manager" that does exactly this. I was looking for a solution along those exact lines and this worked perfectly. It’ll take about an hour to fully get your arms around how it’s hiding the pages / assigning it to users, but once you get it down it’s extremely easy.
I paired it with Peter’s Login Redirect which was a perfect combo. You can basically assign a certain user type to redirect login back to homepage that will then allow that client’s page to become unhidden in whatever menu you’ve created.
Shoot – I was hoping it could be done more from a page standpoint. I can think of several solutions that would work in conjunction, but each of them involve the need to do some custom page trickery for each client page, which it sounds like they may need to set up new pages in the future.