Contact::when($request->client && $request->search, function ($q) use($request) {
    $q->whereHas('companies', function ($q) use ($request) {
        $q->where('is_client', true);
    })->where(function ($q) use ($request) {
        $q->where('first_name', 'like', '%'.$request->search.'%')
        ->orWhere('last_name', 'like', '%'.$request->search.'%')
        ->orWhereHas('companies', function ($q) use ($request) {
            $q->where('name', 'like', '%' . $request->search . '%');
        });
    });
})->when($request->client == null && $request->search, function ($q) use($request) {
    $q->where('first_name', 'like', '%'.$request->search.'%')
        ->orWhere('last_name', 'like', '%'.$request->search.'%')
        ->orWhereHas('companies', function ($q) use ($request) {
            $q->where('name', 'like', '%' . $request->search . '%');
        });
})->when($request->client && $request->search == null, function ($q) use ($request) {
    $q->whereHas('companies', function ($q) use ($request) {
        $q->where('is_client', true);
    });
})
    ->paginate(30)