How to telnet with souce ip or interface (loopbacck) on the fortigate

Dears,

did anyone knows how to telnet with source IP or interface on the FortiGate

like "execute ping-options source <ip-address-of-the-interface>"

Topology:

Client --> ASA<---IPSEC--> Fortigate --> Router1 --> Router2 --> ASA --> Server

the Client can't connect to the server, I have created the loopback (IP of the client) on the R1 and I can telnet to the service port.

I need to telnet from the FortiGate to confirm from my side.