If any of the signer sign the document then the document must be considered as signed.

[Shweta23202883vr97]

I need to send a contract that should be signed by a customer contact and an applicant contact, which is coming from an master object record. 

If any of them sign the document then the document must be considered as signed.

this document will have one signature field in the document, and once it is signed by any of the recipients should be completed.

[jeswong]

Recipient groups is an advanced feature that Adobe Sign supports. Any recipient in the group can sign and "complete" the agreement. To add a recipient group, please see: https://helpx.adobe.com/sign/kb/add-recipient-groups-adobe-sign.html.

If you do not see this feature enabled on the Send page, your account admin will need to enable this feature: https://helpx.adobe.com/sign/kb/enable-recipient-groups-adobe-sign.html