my $input = $ARGV[0];
my %is_subset = map {$_ => 1} powerset(split //, $input);
while (<$dict_fh>) {
    chomp;
    my ($word, $normalized) = split /\t/;
    print $word if $is_subset{$normalized};
}
sub powerset {
    # ...
    return map {join '', sort @$_} @subsets;
}