Convert Query Builder to Eloquent ORM with left join in laravel 5

I have a query using query builder.

my query:

$customer = DB::select(DB::raw('select *, CONCAT(lastname,", ",firstname, " ", if (middlename = null, "", middlename)) as fullname from customer
                                LEFT JOIN
                                (
                                     select id,max(id) as maxCustomer from customer
                                ) c on c.id = customer.id
                                where subscriber_id like "%'.$input.'%"
                                or lastname like "%'.$input.'%"
                                or firstname like "%'.$input.'%"
                                or middlename like "%'.$input.'%"
                                or CONCAT(lastname,", ",firstname, " ",middlename) like "%'.$input.'%"'));

I want to convert it to eloquent because I want to use laravel eager load. When I use $customer->load, it has an error, Call to a member function load() on a non-object. I am having difficulty to convert the left join part to eloquent.

via Chebli Mohamed