my $string_to_find = 'hidden';
my @array_to_search = qw(Foo whathiddenever Bar 12hidden456);

say "Found $_" for grep {m/\Q$string_to_find/} @array_to_search;

##</code><code>##

say "Found $_" for grep {index($_, $string_to_find) > -1} @array_to_search;