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$users = DB::table('users')->whereIn('id', array(1, 2, 3))->get()
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$users = DB::table('users')
->whereIn('id', [1, 2, 3])
->get();
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Make use of Logical Grouping (Laravel 7.x/4.2). For your example, it'd be something like this:
Model::where(function ($query) {
$query->where('a', '=', 1)
->orWhere('b', '=', 1);
})->where(function ($query) {
$query->where('c', '=', 1)
->orWhere('d', '=', 1);
});