use strict;
use warnings;

my @files = qw{ABC DEF GHI JKL MNO PQR STU};
my @need = qw{MNO ABC GHI};
my $need_re = join q{\s.*?} => map { q{\b} . qq{\Q$_\E} . q{\b} } sort @need;

if (join(q{ } => map { qq{\Q$_\E} } sort @files) =~ /$need_re/) { 
    print qq{OK\n};
}   
else {
    print qq{NOT OK\n};
}