where clause in laravel for search

I am trying to select rows from table students using laravel query for searching but on searching it's returning all rows from table.

$data = DB::table('students')
    ->select(['name', 'username'])->where('institute', $inst)
    ->where('username', 'LIKE', '%'.$search.'%')
    ->orWhere('name', 'LIKE', '%'.$search.'%')
    ->orWhere('email', 'LIKE', '%'.$search.'%')
    ->orWhere('contact', 'LIKE', '%'.$search.'%')
    ->orderBy('id', 'DESC')
    ->paginate(10);

via Chebli Mohamed