By design the TextSearchPath property cannot be set to multiple objects in order to use two or more properties of the bound object when filtering the items in the AutoCompleteBox control.
In order to achieve the desired behavior in the RadAutoCompleteBox control you will need to create a custom FilteringBehavior
with the custom logic of the multiple properties filtering. You can check our online SDK example about TwoPropertiesFilteringBehavior
that shows how to achieve the previously described approach.
Hope this is helpful.
All the best,
the Telerik team