Laravel queries - select entries conditionally -

i have query entries in database may have end date set zero. how can following query - want select events where:

a) start date before today, end date set 0 (0000-00-00 00:00:00)

and

b) start date and end date after today

all i've got far select start date after today:

$eventslist = db::table('events')     ->where('start', '>', carbon::now())     ->get(); 

but misses started yesterday don't have end date set.

edit: have added query orwhere clause, orwhere causes return no results:

$eventslist = db::table('events')     ->where('start', '>', carbon::now())     ->orwhere(function($query)   {       $query->where('start', '<', carbon::now())             ->where('end', '=', '0000-00-00 00:00:00');   })     ->get(); 

i guess looking this:

        db::table('events')         ->where(function($query)         {             $query->where('start', '>', carbon::now())                   ->where('end', '>', carbon::now())         }         ->orwhere(function($query)         {             $query->where('start', '<', carbon::now())                   ->where('end', '=', '0000-00-00 00:00:00');         })         ->get();