#!/usr/bin/perl

my @words = qw(we love);

while (<DATA>) {

    # all search words must appear, but order is irrelevant
    my $found = 0;
    for my $search (@words) {
        $found = /\Q$search/i;
        last unless $found;
    }
    print if $found;
}

__DATA__
foo we love bar
love we foo bar
foo love bar we
foo we bar
love foo bar

##</code><code>##

foo we love bar
love we foo bar
foo love bar we

##</code><code>##

open my $fh, "<", $DataIn or die "Couldn't open '$DataIn': $!";

while (<$fh>) {
    ...