use strict;
use warnings;
use 5.010;

my $str ="word1,word2, word3,word4,word5";

my @pieces = split /\b,\b/, $str;

for my $piece (@pieces) {
	say "-->$piece<---";
}


output:
-->word1<---
-->word2, word3<---
-->word4<---
-->word5<---