$s = 'a,b,"hey, you","str1, str2, str3",end';
push @fields, $1 while $s =~ /("[^"]+"|[^",]+)(?:,|$)/g;
print "$_\n" for @fields;

##</code><code>##

$s = 'a,b,"hey, you","str1, str2, str3",end';
@fields = $s =~ /("[^"]+"|[^,]+)(?:,|$)/g;  # Use +, not *, or you get a blank element
print "$_\n" for @fields;

##</code><code>##

a
b
"hey, you"
"str1, str2, str3"
end