Instead of using while on a filehandle, you might take advantage of the $/ operator in a block like this:

{
    local $/;    # undef input record separator
    $clientRequest = <$client>;    # slurp it all in
}
[download]

That'll get you the whole rest of the request in one go, instead of having to append a line at a time.

Jon Udell has a good example of building an HTTP server in Perl with the IO::Socket module, in his dhttp program. (But when I did the same thing, I used HTTP::Daemon.)