Can I use multiple fields in 'lookupfield' attribute for rest api - create/update leads?

[Anonymous]

I am using rest api to create/update lead in Marketo system.
http://developers.marketo.com/documentation/rest/createupdate-leads/
I use custom field called clientid in the attribute 'lookupfield' . Can I have more fields in that attribute? 
 

[Anonymous]

Unfortuantely, it is only possible to use one lookup field in a call.