How to have a sprite with fixed size and position relative to screen resolution?

I’ve been going through this for quite a while now.
Say I have a sprite. And it looks just right in 1366x768 resolution.
When I change the resolution - the sprite changes shape and is in a slightly different position.
I’ve worked with OnGUI and already know how to keep the position, scale, etc. just right, but this is not the same deal.
So, on to the main question - what would be the code that, once attached to the sprites, locks it’s location, size and scale, and looks good on every resolution, plus - the sprite itself still looks good and not pixelated.
I’m using C# and I know this is quite a big and complex code, but if anyone would at least go as far as lead me on the right track - I’d be grateful.

To those who still look for an answer and this might help - I solved the problem.
Add this line to the script on the sprite:

sprite.transform.localScale = new Vector3(Screen.width/1366f, Screen.height/768f,  1);

The sprite should give pixels to units: 1.

The orthographic camera should have this script attached:

camera.orthographicSize = Screen.height / 2;

Once played the sprite stays the same size and looks quite good even in the lowest resolution. Hope this helps those who need to have a fixed size sprite looking crisp and resolution independent!