Everything on the left side of your substitution needs to be a regular expression; special characters need to be escaped, etc.

As toolic points out, quotemeta will ensure all the rules are followed.

An example using quotemeta to ensure grep works properly:

foreach my $searchString (@requestedSearches)
{
    my $searchRegex = quotemeta $searchString;
    my @matchesFound = grep /$searchRegex/, @dataStore;
    ... # Do something with @matchesFound
}
[download]

And, before you ask, no, there is no inverse function to quotemeta, but a search on PerlMonks will reveal some theoretical almost-reverse techniques that could come in handy some day. :-)