How can I clean the text for search using RegEx

Getting Help Code Review
1

I can use the below code to search if the text str contains any or both of the keys, i.e.if it contains “MS” or “dynamics” or both of them

package main

import (
	"fmt"
	"regexp"
)

func main() {
	keys := []string{"MS", "dynamics"}
	keysReg := fmt.Sprintf("(%s %s)|%s|%s", keys[0], keys[1], keys[0], keys[1]) // => "(MS dynamics)|MS|dynamics"
	fmt.Println(keysReg)
	str := "What is MS dynamics, is it a product from MS?"
	re := regexp.MustCompile(`(?i)` + keysReg)
	matches := re.FindAllString(str, -1)
	fmt.Println("We found", len(matches), "matches, that are:", matches)
}

I want the user to enter his phrase, so I trim unwanted words and characters, then doing the search as per above.
Let’s say the user input was: This,is,a,delimited,string and I need to build the keys variable dynamically to be (delimited string)|delimited|string so that I can search for my variable str for all the matches, so I wrote the below:

	s := "This,is,a,delimited,string"
	t := regexp.MustCompile(`(?i),|\.|this|is|a`) // backticks are used here to contain the expression, (?i) for case insensetive
	v := t.Split(s, -1)
	fmt.Println(len(v))
	fmt.Println(v)

But I got the output as:

8
[      delimited string]

What is the wrong part in my cleaning of the input text, I’m expecting the output to be:

2
[delimited string]

Here is my playground

2

I got it done with below playground

package main

import (
	"errors"
	"fmt"
	"regexp"
	"strings"
)

func build(words ...string) (*regexp.Regexp, error) {
	// words to be excluded
	re := regexp.MustCompile(`(?i)^(this|is|a)`)

	var sb strings.Builder

	switch len(words) {
	case 0:
		return nil, errors.New("empty input")
	case 1:
		return regexp.Compile(regexp.QuoteMeta(words[0]))
	}

	quoted := make([]string, len(words))
	for i, w := range words {
		quoted[i] = regexp.QuoteMeta(w)
	}

	sb.WriteByte('(')
	for i, w := range quoted {
		if i > 0 {
			sb.WriteByte('\x20')
		}
		sb.WriteString(w)
	}
	sb.WriteString(`)|`)
	for _, w := range quoted {
		matches := re.FindAllString(w, -1)
		if len(matches) == 0 {
			sb.WriteString(w)
			sb.WriteByte('|')
		}
	}

	return regexp.Compile(`(?i)` + strings.TrimSuffix(sb.String(), "|"))
}

var words = regexp.MustCompile(`\pL+`)

func main() {

	input := "\tThis\v\x20\x20,\t\tis\t\t,?a!,¿delimited?,string‽"
	allWords := words.FindAllString(input, -1)

	re, err := build(allWords...)
	if err != nil {
		panic(err)
	}

	fmt.Println(re)

	str := "This is a delimited string, so let's go"
	matches := re.FindAllString(str, -1)
	fmt.Println("We found", len(matches), "matches, that are:", matches)
}

Output:

(?i)(This is a delimited string)|delimited|string
We found 1 matches, that are: [This is a delimited string]