Sharepoint REST calls with SAML tokens

We are building a standalone webapp using php. My setup is as follows.

• We have office 365 account that is synced to AD from Azure.
• We are using OKTA as our IDP.
• In my app I am using SAML to get an assertion from OKTA. After authenticating from my app the users able to login automatically when they go to the sharepoint account.
• I am able to make REST calls from the APP to the sharepoint online and fetch data (Using username and password).

Now I would like to make REST calls to the sharepoint API using the SAML tokens.

I would like to know

• Does sharepoint2013 online REST supports SAML tokens.
• If yes, what are the headers that I should pass and what is the format of values to pass in the header.

Thanks in advance.