How do I perform search on multiple relations deep?

I have 3 tables employees, companies, and cities

class EmployeeRepositoryEloquent extends BaseRepository implements EmployeeRepository
{

public function model()
{
return Employee::class;
}

protected $fieldSearchable = [
'name',
'email',
'company.name'=>'like',
'**company.city.name**'=>'like'
];

How can I perform the search on city name?