A simple $t_subject =~ /foo/ will tell you if "foo" appears in the string. If "foo" might have special characters you want to match literally, /\Qfoo\E/ or just /\Qfoo/ or using quotemeta is necessary.

For multiple matches, it depends on the logic. If you want to match on any one, you could simply do

if (grep { $t_subject =~ $_ } qr/foo/, qr/bar/, qr/baz/) {

or

if (grep { $t_subject =~ $_ } map quotemeta, 'foo', 'bar', 'baz') {

On Perl 5.10 and later, you could even do

if ($t_subject ~~ [qr/foo/, qr/bar/, qr/baz/]) {