I have an admin account that can access everything on that folder. However my client want another account that can also access all of the files in the folder except for 3 files.
I was almost afraid to mention the environmental variable because, while I know about it, I’ve never had the need to use it. Because I’m headed out the door in a minute, let me suggest a thorough read of http://httpd.apache.org/docs/2.2/mod/mod_rewrite.html, thorough because you need to read ALL the page (past the Environmental Variable section) to see that you can set and modify your own variables. You should consider HOW to do that dependent upon the access (which I don’t have my head around just now).
Alternatively, the way that I would approach it is to use $_SESSION variables to identify the full access and limited access and check upon entry to every sensitive page (I do that, typically, for website backends so my client can have multiple people accessing it but not getting access to everything, i.e., prevent unauthorized changes).
I’m sure that there’s a “cutsie” way to use Apache to do that for you but, as far as I’m concerned, there’s nothing like a hammer to drive a nail and PHP’s sessions are excellent like that.