#! perl -slw
use strict;

my $left_text   = [ qw{ when rome romans} ];
my $right_text  = 'When in Rome, do as the Romans.';

my $regex = '(?:\b' . join( '\b|\b', map quotemeta, @$left_text ) . '\b)';
print $regex;

my $found = () = $right_text =~ m/$regex/ig;

print $found ? 'matched: ' : 'Not matched', $found;

__END__
C:\test>junk42
(?:\bwhen\b|\brome\b|\bromans\b)
matched: 3