import { Pipe, Injectable, PipeTransform } from '@angular/core';
import { DomSanitizer } from '@angular/platform-browser';

@Pipe({
 name: 'keyword'
})
@Injectable()
export class KeywordPipe implements PipeTransform {
 constructor(private sanitizer: DomSanitizer) {
 }

 transform(val: string, keyword: string): any {
 const Reg = new RegExp(keyword, 'i');
 if (val) {
 const res = val.replace(Reg, `<span style="color: #81E1B7;">${keyword}</span>`);
 console.log(res);
 return this.sanitizer.bypassSecurityTrustHtml(res);
 }
 }
}

<ion-label [innerHTML]="item.name | keyword:searchText"></ion-label>