Have a look at the demo for an example implementation.
You will need to implement the following things for this to work
Sample_Request.RequestName like "%" + SearchTerm + "%" or Sample_Request.Id = CurrentRequestId
Implement ItemSelected to set the CurrentItemId, convert to the correct entity ID type
Implement SearchUpdated method to update local variable and refresh the query
Implement ClearItemClick, to set the current item back to null
Map the query to the input of the AsyncTypeahead WebBlock. Map the Id to the ID, and whatever you want as the displayName to the display name
That's it! If you have any issue send me through a question