You can try with a PBR, applying as local policy via CLI Addon:
ip access-list extended PBR
10 permit ip host [HOST_IP] any
ip local policy route-map PBR
route-map PBR permit 10
match ip address PBR
set ip next-hop [NEXT-HOP]
Note that if your next-hop is in a service VPN, you must specify it:
set ip vrf [ID] next-hop [NEXT-HOP]
If you are looking for something at the Overlay level, you can use a Traffic Data/Data Policy by matching the client's IP and in action, selecting a TLOC List:
data-policy [NAME]
sequence [ID]
match
source-ip [USER_IP]
!
action accept
set
vpn [VRF_ID]
tloc-list [TLOC_LIST_for_overlay_PBR]
!