In case you want to match either ( or " (either/any of them), you can use a character class like this:

use strict;
use warnings;
use Data::Dumper;

my $grepper = 'label[("]';
my @array = qw ! label( label" label% label!;
my @LABEL = grep /$grepper/, @array;

print Dumper $grepper, \@array, \@LABEL;
[download]

gives

$VAR1 = 'label[("]';
$VAR2 = [
          'label(',
          'label"',
          'label%',
          'label'
        ];
$VAR3 = [
          'label(',
          'label"'
        ];
[download]