"...this is beyond my abilities at this point..."

Scale the problem back to your actual abilities and start from there. If you are confused by complex regular expressions (like I often am), break the problem down into simpler ones until you are more familiar (note: this example only finds words that are near but appear after your search term):

use strict;

=pod
 ...if either revenue(s), sales or growth occur within three words of 
+the word currency or the phrase "foreign exchange."
=cut

my @sources = ('foreign exchange','currency');

my $sourceData = <<EOF;
foreign exchange revenue wordiness happycat smiles
currency revenue world cat blue runny
a nice happy foreign exchange said that revenues would be up
the day I last visited my foreign exchange they said revenues were goo
+d
wow currency makes good growth
when currency came revenues dipped
EOF

my %searchvector = map {$_=>$_} qw|revenue sales growth|;

my $cntFound = 0;

for (@sources)
{
   while($sourceData=~m/$_\s+(\w+)\s*(\w+)?\s*(\w+)?\s*/g) #does the w
+ord appear?
   {
        # is anything in the searchvector in the found words?  
       for ($1,$2,$3)
       {
           my $r = $_;
       $r=~s/revenues/revenue/;
           if($searchvector{$r}){++$cntFound};
       }
                
   }

}

print qq|Total times search (| . (join ' ', (values %searchvector)) . 
+') found: ' . $cntFound . qq|\n|;

1;
[download]

Total times search (growth sales revenue) found: 6
[download]