From PerlNet

One of the goals of this project is to add a -k option to perldoc, for keyword searching. A preliminary version is already ready, which you can find in the development snapshot.

If you just want to see how it's supposed to work without having to download anything, a simple CGI wrapper around perldoc -k exists at:

 http://pod-indexing.annocpan.org/perldoc-k.cgi

Note that the "keywords" can also be special characters; for example, see this search for &.