Ok, so let's define omniscient.
That is, having knowledge of everything.
And that INCLUDES your flawed protagonist and how they see things.
So you can present their viewpoint, what they see as how they see it,for the most part.
So something like this:
Ignoring the hunger in his belly, he patched his shoes diligently,
in the belief that when all the holes merged together he would use the shoe
fund he had gathered over several years by slipping coins in between
the floorboards, though he was unaware that jingle of coins had
alerted his landlord long ago, and that fund was regularly raided.
So basically we have facts about someone else that the main character does not know (the "little did he know..." omniscient signifier), but we aren't head hopping--that is, while we know the landlord became aware and stole, we don't know his thought process, while we are more intimately connected with the poor main character.
So what you really have is an omniscient viewpoint with a specific interest in the protagonist's point of view and life.
You can also have the "protagonist isn't there" and "protagonist didn't see" or "the protagonist ignored."
The protagonist isn't there basically goes like this, though there are many variations:
Minutes before Shoeless Joe stepped on the street, while he was taking
a hot sudsy shower, children played in the street...
His not being there makes the POV clear, but we still get a detail about Joe.
You can also switch narrative distance. The upshot from the article is this, several lines from the same story:
- It was winter of the year 1853. A large man stepped out of a doorway.
- Henry J. Warburton had never much cared for snowstorms.
- Henry hated snowstorms.
- God how he hated these damn snowstorms. Under your collar, down inside your shoes, freezing and plugging up your miserable soul.
One of these is a "wide angle" POV so to speak, and the last closes in on Henry for a "close up" of his POV. You can basically treat POV like a camera, closing in or panning out with a smooth transition.
So you can do that. Also, in the movies, when things go black for a split second, being in a totally different place and scene is expected--transitional breaks in books, such as spacing, chapter breaks and other typographical cues for the reader to get ready for something new.