Naby Keita and Roberto Firmino struck inside the first 26 minutes to put the hosts in command and Liverpool's only regret may be not building a more emphatic lead to take to northern Portugal for next week's second leg.
Klopp said it was a "really, really good result". The Egyptian was alert to pounce on a loose back-pass and shrugged off the covering Felipe, only to slide the ball past Casillas and the post when he looked destined to score.
Firmino was on hand to take advantage of a cross from Trent Alexander-Arnold and made no mistake as he turned the ball home from close range.
The goals, naturally, will steal the attention, but Keita at his best will offer so much more. It is Liverpool's evolution under Klopp that is the greatest victory of all.
In addition, Henderson chipped a ball to Firmino for another first-half chance and curled in an excellent cross after the break, only for Sadio Mane to be ruled narrowly offside after volleying into the net.
"We hoped it would be like this because the last game he got better and better until the last minute so we wanted to build on that", said Klopp.
Salah happy and proud to break Liverpool record
The performance was not at the top level but at this stage it is about fighting. "People want us to play like Manchester City ". Salah has been criticised in recent weeks for being too selfish in front of goal in desperation to end his scoreless streak.
There were a few good performances around as Liverpool shut out the Porto attack, linked up well in midfield and were clinical in front of goal. His goal was lovely.
Porto: Tough task. A draw, especially one with goals, will feel like a win. It comes from a corner that Liverpool can't clear.
FW Divock Origi, N/R - The Belgian has played his way back into Klopp's thoughts and is getting fairly regular playing time of late. He obviously likes that position, so it was my fault that he played for one and a half years as a [No.] 6.
"Sorry about that, but we needed him there".
FC Porto won their previous match as they Boavista at home. Porto played their part in an entertaining game Tuesday and had numerous chances to grab a vital away goal, but having kept a clean sheet, the Merseysiders will now be strong favourites to go through to the last four.
So far have Liverpool come in the past year that a trickle of fans in red were still casually taking their seats with seconds to go before kick-off. James Milner played a attractive long ball out on the other wing to Sadio Mane, who dribbled past a couple of defenders before finding Firmino in the box, and the Brazil forward laid the ball off to the onrushing Keita on the edge of the area whose heavily deflected shot bamboozled Iker Casillas and went in to the back of the net.