Something like this?

use strict;
use warnings;

my $line = 'logfile = filename   ,  abcd=eflk , cxd';

my $file;

if ($line =~ /logfile\s*\=\s*(.+?)\s*\,?/){

$file=$1;

}

print "logfile=$file";

output:
=======
logfile=filename
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