my $vndr_key = (grep { $args->{desc} =~ m/$_/i } keys %vendors)[0];

if ($vndr_key ne '') {
  #do something
} else {
  #do something else
}

##</code><code>##

my $vndr_key_count = grep { $args->{desc} =~ m/$_/i } keys %vendors;

if ($vndr_key_count) {
  #do something
} else {
  #do something else
}

##</code><code>##

my $re = join '|', keys %vendors;
my $vndr_key_found =  $args->{desc} =~ /$re/;
if($vndr_key_found) { ... } else { ... }