Hi Kamesh,
No there is no T-Code for this, this is Query string parameter you can send with your WD application URL.
Please have look to below url:
http://help.sap.com/saphelp_erp60_sp/helpdata/en/ce/3dd23a09313b37e10000000a11405a/content.htm
SAP URL Parameters - Web Dynpro for ABAP - SAP Library
Ex:
http://<your domain url>:<port>/sap/bc/webdynpro/<your app name>?sap-client=130&sap-language=EN&sap-wd-configId=<your config id>
If above url you will run in Browser then this will hit Client 130 if you will put sap-client=100 then this will hit Client 100 code.
Hope this will help.
Thanks-
Abhishek