foreach ($a, $b, $c) {
   next unless /abcdefgh/;
   ...
   last;
}

##</code><code>##

if (grep /abcdefgh/, $a, $b, $c) {
   ...
}

##</code><code>##

use List::MoreUtils qw( any );

if (any { /abcdefgh/ } $a, $b, $c) {
   ...
}