The below post explains steps to divert syslog to different files for each client.
1. Open and edit /etc/rsyslog.conf, then add below lines:
$template FILENAME,"/var/log/%fromhost-ip%/messages" *.* ?FILENAME
2. Restart rsyslog service to take effect:
# systemctl restart rsyslog.service
or
# service rsyslog restart
3. Each of client’s messages will be generated dynamically depending on client’s IP address, for example:
/var/log/192.168.1.2/messages