Something along these lines -
192.168.168.0/24 seems a bit smallish; if you need to, then make an object-group for them too.
same-security-traffic permit intra-interface
object-group network Client_Networks
! Load up client network assignments here, so the ACLs don't get huge:
network-object 192.0.2.0 255.255.255.0
network-object 198.51.100.0 255.255.255.0
! ACL for tunnel to an example client - this one's on the 192.0.2.0 range.
! The entry covers traffic between the local net and the client
access-list outside_cryptomap_client_1 extended permit ip 172.16.89.0 255.255.255.0 192.0.2.0 255.255.255.0
! And this is needed for the traffic between the employee nets and the client
access-list outside_cryptomap_client_1 extended permit ip 192.168.168.0 255.255.255.0 192.0.2.0 255.255.255.0
! ACL for the tunnel to an employee - we'll stick them on 192.168.168.32/30;
! For the purposes of the tunnel, the client networks are local networks.
! The entry's going to create a ton of IPSec SAs -- makes a mess, but not a lot of choice.
access-list outside_cryptomap_employee_1 extended permit ip object-group Client_Networks 192.168.168.32 255.255.255.252
! And, the local whatnot.
access-list outside_cryptomap_employee_1 extended permit ip 172.16.89.0 255.255.255.0 192.168.168.32 255.255.255.252
! all the other config for the site-to-site tunnels..
crypto map outside_map 1 match address outside_cryptomap_client_1
crypto map outside_map 501 match address outside_cryptomap_employee_1
And if you have any NAT whatsoever going on, which you probably do since you're using RFC1918 ranges, you need NAT exemptions all around, matching all the traffic in your crypto ACLs.
! add to an existing NAT exemption ACL, if you have one. Otherwise, make one..
! local to clients
access-list outside_nat0_outbound extended permit ip 172.16.89.0 255.255.255.0 object-group Client_Networks
! local to employees
access-list outside_nat0_outbound extended permit ip 172.16.89.0 255.255.255.0 192.168.168.0 255.255.255.0
! employees to clients
access-list outside_nat0_outbound extended permit ip 192.168.168.0 255.255.255.0 object-group Client_Networks
nat (Public) 0 access-list outside_nat0_outbound
Of course, you'll need to configure the remote VPN endpoint at the employee's location to have the client networks as a remote network, matching the crypto ACL for the site-to-site connection to them.