foreach my $records(@merged_array){
    
    if($records =~ /$sample_ids[3]/){
        print $records;
    }
}

##</code><code>##

foreach my $records (@merged_array) {
    my @elements = split /,/, $records;

    for my $sample_id (@sample_ids) {
        if ($elements[3] =~ /$sample_id/) {
            print $records;
        }
    }
}