use strict;
use warnings;

my $max = 4;  #Largest expected index.

while (<DATA>) {
    s/#.*$//;  #Clear out the comments
    chomp;
    my @foo = split /,/;
    my $company = $foo[1]; #prime a variable with a company name
    if ($#foo > $max) {        #If there are more elements than the max...
        my $range = (scalar @foo) - $max; #Get the top of the range
        $company = join '+', @foo[1..$range]; #The company name is in a slice
    }
    print "$company\n";
    #do whatever with the data.
}

__END__
client,ABC Company, jwilkens,jdoe,mdeart #this one is fine
client,Cornell,Thayil,Cameron & Sheppard, LLC, klivingston,amarison,pserton #thi
s one is not
client,Doe,Smith & Randall, Inc, jwaters,pfloyd,jjoplin #this one is not